1488

ARBORETUM AND FRUTICETUM.

PART ID.

In these instances, the pedicel is often a little longer, and the capsules moreslender.

“ The colour of the young shoots varies greatly, often so much as to causethe varieties to appear distinct species. The branchlets of S. alba are eitherhrown, or, as in the var. vitellina, of a yolk-of-egg or a red brick colour; andthere is a different shade of yolk-of-egg colour in ,S'. repens, and S, rosmarini-folia ( S . lae'ta Schultz). Many species, when carefully examined, will be foundto vary in colour, though only to a small extent. The branches of S. purphreaare of a coral colour, rarely of a dark yellow, and sometimes white, coveredwith a reddish bloom. S. omygdalina has the shoots sometimes of a brownishyellow, and sometimes of a brownish black.

“ The form of the leaves in the same species, and even in the same plant, cannever be depended upon. In S. phylicifdlia, S. myrtilloides, S. arbuscula, andS. repens, they vary from narrow-lanceolate and being attenuated towardsthe base, in the three last-named species, to roundish-ovate and being cordate-emarginate at the base. In some species, the form of the leaves is almostalways the same, as in S. viminalis, S. incana, and S. /Hppophaefolia. Inother species, the leaves vary ; being serrated, or entire, green or hoary on theunder surface, and glabrous or hairy, on the same plant. The same variation iscommon on the exterior of the ovaries; which, in S. yohylicifolia, are some-times glabrous, and sometimes hairy; some individuals of this species havinghalf the ovary hairy, and the other half glabrous; while in others there is onlya hairy or downy line. In certain species, however, these variations are neverfound, or very rarely ; although in S. viminalis ovaries partly naked, andpartly downy, occur. The brown tip of the bracteas of the flowers, in somespecies, turns paler, and in others red, or even purple; which is another causeof uncertainty in specific distinctions. The bracteas are sometimes obovate,and only half the length of the ovary; and sometimes, in the same species,lanceolate, and reaching as far as the style. The style and stigma likewisevary in length, and are occasionally more or less cleft; yet both these organsafford most useful characteristics. The style often appears shorter from beinghidden by the long hairs of the ovary. Stigmas of a rose colour, and of ayellow colour, have been found in the same species. The stipules vary in she,but,never in form ; hence they afford the very best characteristics for distin-guishing species. In no species can these be said to be wanting; and, thoughon old plants they are often not seen, such plants, when cut down, send upyoung shoots which produce leaves attended by stipules of an extraordinarysize. The buds are always 1-valved; and the valves are often cleft at the tip,and sometimes as far as the base; though sometimes, on the same individual,they are undivided. The folding of the leaves in the bud is, most probably,constant, although different in the various species: but this I cannot affirmas certain, not having examined the leaf buds of a sufficient number of specif

“ The variation of the different parts is not the only difficulty with which thebotanical student, in this genus, lias to contend: the great number of hy-brids, the existence of which in the genus iSalix no one can doubt, is anotherobstacle. Nobody will accuse me of arrogance in assuming to know S. rubraand S, viminalis. On the banks of the Rednitz, near Erlangen , there are ma n )thousand trees of these two species; and, at the same time, many intermediateforms, which I can refer to neither species. The catkins of these afford nodistinguishing marks; for what seem at one time to belong to the fon> elspecies, at another time appear more nearly allied to the latter.” Koch con-cludes by stating that, in his Commentary, the species have been arranged,10 groups ; and that no kind has been admitted as a species that he has thimself seen and examined. He has added but few varieties, “ althoughimmense number of no importance might have been adduced; being convinc ■from daily observation and experience, that the multiplication of varieties,stead of rendering any intricate genus more clear, only involves it in a gf eadifficulty.” ■ „ ^

The species of Koch, besides being identified with those of the Af <